p^2-(2a-b)p-2ab

1-(m^2+n^2)-2mn
= 1-(m^2+n^2+2mn)
=1-(m+n)^2
=(1+m+n)(1-m-n)

ax^2+bx^2-cx^2+ax+bx-cx
=(a+b-c)x^2+(a+b-c)x
=(a+b-c)(x+1)x

ax^2+bx^2-b-a+cx-c
=(a+b)x^2-(a+b)+c(x-1)
=(a+b)(x^2-1)+c(x-1)
=(a+b)(x+1)(x-1)+c(x-1)
=(x-1)[(a+b)(x+1)+c]

m^2-2mn+n^2-5m+5n+6
=(m-n)^2-5(m-n)+6
=(m-n-3)(m-n-2)

1-(m^2+n^2)-2mn =1-(m^2+n^2+2mn)
=1-(m+n)^2
=(1-m-n)(1+m+n)
ax^2+bx^2-cx^2+ax+bx-cx =ax(x+1)+bx(x+1)-cx(x+1)
=x(a+b-c)(x+1)
ax^2+bx^2-b-a+cx-c=a(x^2-1)+b(x^2-1)+c(x-1)
=a(x-1)(x+1)+b(x-1)(x+1)+c(x-1)
=(x-1)(ax+a+bx-b+c)
m^2-2mn+n^2-5m+5n+6=(m-n)^2-5(m-n)+6
=(m-n-2)(m-n-3)

（1+m+n)(1-m-n)
x(x+1)(a+b-c)
(x-1)[(a+b)(x+1)+c]
(m-n)(m-n-5)+b
最后一道题好像抄错题了吧？哈哈，只能做到这一步了！

什么问题？